The Difference between Steel Strand, Steel Core Aluminum Strand and Aluminum Clad Steel Core Aluminum Strand

Steel Strand

A steel product called steel strands is created by twisting lots of steel wires together. Galvanized, zinc-aluminum alloy, aluminum, copper, epoxy resin, and other coatings can be put to the surface of carbon steel as needed.

According to the number of steel wires, galvanized steel strand and aluminum-clad steel strand for electric power are also divided into 2, 3, 7, 19, 37, and so on, which the most prevalent type is 7-wire structure.

Monofilament and stranded wire are produced using different stages of the strand manufacturing process, while monofilaments are produced using (cold) drawing technology. High carbon steel coils, stainless steel coils, or medium to low carbon steel coils can all be used as the material, depending on the end-use of the strand. The monofilament should be electroplated or hot plated if galvanization is necessary.

Steel Core Aluminum Stranded Wire

There are two stranding methods for steel-core aluminum strand: non-twist stranding and twist-free stranding. The cores stranded by the untwisted method have no torsional internal stresses and are therefore mainly used for uncompressed multi-stranded wires to prevent internal stresses from dispersing when a single wire breaks. Untwisted stranding is mostly used for tightening molded wire cores because the residual stresses generated by self-twisting are elastic deformations, while molded are plastic deformations, so the internal stresses can disappear after tightening.

Whether the twist direction of the steel-core aluminum stranded wire is concentric stranding or composite stranding, the outer layer is designated as the right (Z-shaped); the outer layer of the stranded insulated wire is the left (S-shaped). Whether right or left, its two adjacent layers twist in opposite directions. This is to unify the product, facilitate connection and prevent loosening of the single conductor. The tensile die is an important control point for steel-core aluminum strand: the uniformity of the diameter of the steel-core aluminum strand, the presence of snaking, missing roots and jumps are shown here.

Aluminum and steel stranded wire are combined to create steel-core aluminum stranded wire, which is ideal for overhead transmission lines. According to our understanding, the external aluminum wire was wrapped tightly around the inside steel "core"; this allowed the steel core to primarily serve as a means of strengthening the aluminum strand while simultaneously serving as a means of power transmission.

Aluminum-coated steel-core aluminum stranded wire

The raw materials for the production of aluminum-coated steel-core aluminum strand include aluminum, steel wire and copper. Among them, aluminum is the main raw material because of its good electrical conductivity, while the light weight is also an advantage. Steel wire is used to increase the strength and rigidity of the strand, while copper is used to improve electrical conductivity and corrosion resistance.

The production process of aluminum-clad steel-core aluminum strand is divided into the following steps:

Steel wire twisting: First, the high-strength steel wire is subjected to a series of processes, including twisting and galvanizing, to increase its strength and corrosion resistance.

Aluminum cladding: The wire is coated with a layer of aluminum, a process called aluminum cladding, which aims to protect the wire from oxidation and corrosion, and also increases the adhesion of aluminum and steel wire.

Stranding: The aluminum-clad steel wire is mechanically stranded to form stranded wire. In this process, the stranding distance, direction and number of stranding layers will have an impact on the performance of the stranded wire.

Extrusion package: the strand will be coated with a layer of aluminum, the process is called extrusion package, its purpose is to protect the strand from damage and corrosion, but also to increase the adhesion of aluminum and strand.

Heat treatment: the extruded strand will be heat-treated to eliminate internal stress and improve the strength and stability of the material.

Packaging: The heat-treated aluminum-clad steel-core aluminum strand is cut and packaged according to certain lengths and specifications for transportation and use.

The production process of aluminum-clad steel-core aluminum strand needs to be optimized and controlled to ensure its performance and quality. Among them, the process optimization mainly includes the optimization of steel wire, aluminum cladding and stranding process parameters, in order to improve the performance of aluminum cladding and stranding such as adhesion and strength. Process control includes the control and monitoring of the entire production process to ensure that the produced aluminum-clad steel-core aluminum strand meets the relevant standards and specifications.

In terms of process optimization, the pretreatment of the steel wire is very important because it directly affects the quality of the aluminum cladding. If the surface quality of the steel wire is not good, the adhesion between the aluminum ladle and the steel wire will be reduced, which will lead to a reduction in the strength and stability of the strand. Therefore, during the pre-treatment of the wire, proper cleaning and de-oiling are carried out to ensure that the surface of the wire is clean, smooth and has good adhesion to the aluminum ladle. In terms of the process parameters of the aluminum cladding and strand, factors such as the thickness of the aluminum cladding, the strand spacing and the number of layers of the strand will have an impact on the performance of the aluminum clad steel cored aluminum strand. In the process of process optimization, the performance of aluminum clad and stranded wire needs to be achieved through reasonable parameter selection and adjustment.